RE-MRU of metadata tracks to reduce lock contention

Abstract

For reducing lock contention on a Modified Least Recently Used (MLRU) list for metadata tracks, upon a conclusion of an access of a metadata track, if one of the metadata track is located in a predefined lower percentile of the MLRU list, and the metadata track has been accessed, including the access, a predetermined number of times, the metadata track is removed from a current position in the MLRU list and moved to a Most Recently Used (MRU) end of the MLRU list.

The invention claimed is: 
     
       1. A method for reducing lock contention on a Modified Least Recently Used (MLRU) list for metadata tracks by a processor device, comprising:
 upon a conclusion of an access of a metadata track, the metadata track holding information associated with at least one data track, if one of:
 the metadata track is located in a predefined lower percentile of the MLRU list, and 
 the metadata track has been accessed, including the access, a predetermined number of times, 
 
 the metadata track is removed from a current position in the MLRU list and moved to a Most Recently Used (MRU) end of the MLRU list; 
 determining if the metadata track is located in the predefined lower percentile, and a number of current accesses for the metadata track; wherein determining the number of current accesses further includes, if the metadata does currently exist on the MLRU list, performing:
 incrementing the number of current accesses, 
 performing a modulo with a predetermined number as a function of the number of current accesses, and 
 if a result of the function is zero (0), removing the metadata track from the current position and moving the metadata track to the MRU end; and 
 
 determining, following the access, if the metadata track currently exists on the MLRU list; wherein if the metadata track does not currently exist on the MLRU list, the metadata track is added to the MRU end of the MLRU list. 
 
     
     
       2. The method of  claim 1 , wherein determining if the metadata track is located in the predefined lower percentile further includes updating a current sequence number associated with the metadata track. 
     
     
       3. The method of  claim 2 , wherein determining if the metadata track is located in the predefined lower percentile further includes, if the metadata does currently exist on the MLRU list, further including determining if the metadata track is located in the predefined lower percentile by determining a current location of the metadata track as a function of the current sequence number of the metadata track, a sequence number of an additional metadata track currently on the MRU end of the MLRU list, and a sequence number of an additional metadata track currently on the LRU end of the MLRU list. 
     
     
       4. A system for reducing lock contention on a Modified Least Recently Used (MLRU) list for metadata tracks, comprising:
 a processor device, operable in a multi-core computing storage environment, wherein the processor device, upon a conclusion of an access of a metadata track, the metadata track holding information associated with at least one data track, if one of:
 the metadata track is located in a predefined lower percentile of the MLRU list, and 
 
 the metadata track has been accessed, including the access, a predetermined number of times, 
 
       removes the metadata track from a current position in the MLRU list and moves the metadata track to a Most Recently Used (MRU) end of the MLRU list;
 determines if the metadata track is located in the predefined lower percentile, and a number of current accesses for the metadata track; wherein determining the number of current accesses further includes, if the metadata does currently exist on the MLRU list, performing:
 incrementing the number of current accesses, 
 performing a modulo with a predetermined number as a function of the number of current accesses, and 
 if a result of the function is zero (0), removing the metadata track from the current position and moving the metadata track to the MRU end; and 
 
 determines, following the access, if the metadata track currently exists on the MLRU list; wherein if the metadata track does not currently exist on the MLRU list, the metadata track is added to the MRU end of the MLRU list. 
 
     
     
       5. The system of  claim 4 , wherein the processor device, pursuant to determining if the metadata track is located in the predefined lower percentile, updates a current sequence number associated with the metadata track. 
     
     
       6. The system of  claim 5 , wherein the processor device, pursuant to determining if the metadata track is located in the predefined lower percentile, if the metadata does currently exist on the MLRU list, determines if the metadata track is located in the predefined lower percentile by determining a current location of the metadata track as a function of the current sequence number of the metadata track, a sequence number of an additional metadata track currently on the MRU end of the MLRU list, and a sequence number of an additional metadata track currently on the LRU end of the MLRU list. 
     
     
       7. A computer program product reducing lock contention on a Modified Least Recently Used (MLRU) list for metadata tracks by a processor device, the computer program product comprising a non-transitory computer-readable storage medium having computer-readable program code portions stored therein, the computer-readable program code portions comprising:
 a first executable portion that, upon a conclusion of an access of a metadata track, the metadata track holding information associated with at least one data track, if one of:
 the metadata track is located in a predefined lower percentile of the MLRU list, and 
 the metadata track has been accessed, including the access, a predetermined number of times, 
 
 removes the metadata track from a current position in the MLRU list and moves the metadata track to a Most Recently Used (MRU) end of the MLRU list; 
 a second executable portion that determines if the metadata track is located in the predefined lower percentile, and a number of current accesses for the metadata track; wherein determining the number of current accesses further includes, if the metadata does currently exist on the MLRU list, performing:
 incrementing the number of current accesses, 
 performing a modulo with a predetermined number as a function of the number of current accesses, and 
 if a result of the function is zero (0), removing the metadata track from the current position and moving the metadata track to the MRU end; and 
 
 a third executable portion that determines, following the access, if the metadata track currently exists on the MLRU list; wherein if the metadata track does not currently exist on the MLRU list, the metadata track is added to the MRU end of the MLRU list. 
 
     
     
       8. The computer program product of  claim 7 , further including a fourth executable portion that, pursuant to determining if the metadata track is located in the predefined lower percentile, updates a current sequence number associated with the metadata track. 
     
     
       9. The computer program product of  claim 8 , further including a fifth executable portion that, pursuant to determining if the metadata track is located in the predefined lower percentile, if the metadata does currently exist on the MLRU list, determines if the metadata track is located in the predefined lower percentile by determining a current location of the metadata track as a function of the current sequence number of the metadata track, a sequence number of an additional metadata track currently on the MRU end of the MLRU list, and a sequence number of an additional metadata track currently on the LRU end of the MLRU list.